1. Field of the Invention
The present invention relates in general to an apparatus for processing and assembling radial lip shaft seals.
2. Description of Prior Developments
An automotive transmission shaft generally has a section exposed to the ambient at the point where the shaft emerges from the transmission housing. Under conventional practice, the joint between the rotary transmission shaft and the associated transmission housing is sealed by an annular sealing unit such as a transmission seal which is clamped or otherwise secured to the end face of the housing.
The transmission seal commonly includes an annular metal case having a circular side wall and an outwardly extending flange which provides a mounting surface for the metal case. The transmission seal further includes an annular elastomeric boot secured to the metal case by tangs or stakes formed integrally with the case side walls. An annular staking tool is driven axially against an end edge of the seal case side wall to form and bend the tangs into engagement with the boot side wall such that the boot is securely anchored to the metal case.
The metal case includes a radially inwardly directed wall that supports an elastomeric sealing lip which is engagable against the rotating transmission shaft. The boot also has an inturned auxiliary lip that engages the rotating shaft. The transmission shaft sealing unit thus has multiple seal contact zones with the rotating shaft so as to prevent liquids or solids from passing across the shaft-housing interface. The shaft is oriented to rotate around a generally horizontal axis.
Over time, a gap or clearance can develop between the shaft surface and the inturned lip on the elastomeric sealing boot. Atmospheric water can condense or migrate into the vacant space within the boot. Water can collect within the boot and adversely affect the performance of the sealing unit.
In order to prevent the accumulation of water in the boot, it is conventional practice to provide a small drain hole in the boot side wall. By locating the sealing unit so that the drain hole is on the undersurface of the unit, any water originating or migrating into the boot will be drained out of the boot without accumulating within the boot.
In order for the drain hole to operate in the intended manner, the sealing unit must be mounted on the transmission housing so that the drain hole is on the undersurface of the sealing unit, i.e. at the six o'clock position when viewed along the shaft axis. In some cases, the sealing unit has been found to be installed incorrectly. In an effort to ensure correct positioning of the sealing unit, it has been a practice to form a locator notch on the flange of the metal case at a point directly opposed to the location of the drain hole in the sealing boot.
The person installing the sealing unit on the transmission housing is instructed to position the unit so that the locator notch in the flange of the metal case is oriented on the upper side of the unit, i.e. at the twelve o'clock position when viewed along the shaft axis. The person installing the sealing unit can readily view the locator notch and be assured that the drain hole is in the correct position if the sealing unit is installed with the locator notch at the twelve o'clock position. The installer does not have to peer underneath the sealing unit to view the drain hole.
Under conventional practice, the locator notch and the drain hole are formed separately at different locations by different tools. The sealing unit is repositioned to permit the separate operations of punching the drain hole in the sealing boot and stamping the locator notch in the metal case flange. Occasionally, through human error, one of the operations will be omitted or misaligned leading to a defective part or defective or unsatisfactory installation. For example, in some cases the locator notch has been misaligned with the drain hole causing the drain hole to be located at an incorrect position such as at the three o'clock or nine o'clock position, thereby preventing effective drainage through the drain hole.